Video on demand (VOD) and audio on demand technologies allow users to select and view/listen to video or audio content at their convenience. On demand systems can be implemented to stream content, which allows a user to view/listen as the content is being streamed, or to download content to a device, such as a computer or digital video recorder (DVR), for viewing/listening at any time. A DVR is a device that records video and audio content in a digital format to a disk drive or other memory medium within the device. DVRs include software for personal computers which enables video content capture and playback to and from the memory medium. DVRs can provide the user with functionality, including play, pause, stop, fast-forward and rewind. Such functionality can enable a user to pause a live video content stream for viewing at a later time. Alternatively, a user can record the live video content stream using the DVR and can playback the recorded video content at any time. DVR functionalities also include enabling a user to seek backwards and forwards within the content stream to view previously played and yet unplayed content.
Many internet service providers (ISPs) offer VOD streaming, whereby a user buys or selects video content and it begins to play almost instantaneously, and/or downloading to a DVR for viewing in the future. VOD streaming is a one-way video transmission over a data network, including the Internet, used to play video clips and video broadcasts. Unlike VOD downloading, whereby movie files are played after the entire file has been downloaded and stored, VOD streaming enables videos to be played shortly after only a small amount of content has been received. VOD can also be employed through a two-tier client-server software architecture model. In a client-server relationship, one computer program, the client, makes a service request from another computer program, the server. The server can provide services to the client computer and its users. Several standard network functions, such as email exchange, web access and database access are based on the client-server model. In addition to the standard network functions, the client can request VOD streaming and/or downloading from the server.